Fail rake if manifest is out of date
Manifest update
Organize rake tasks

Definitions up top, dependency bindings down below.
Add post install message to gem #152
Merge pull request #195 from matschaffer/issue/manifest-checking-195

Make manifest updates more obvious
Merge pull request #152 from matschaffer/issue/post-install-152

Recommend removing old gems on installation
Pre-release prep